I've been having horrible Fusion performance(phone and DSL) so I had Sonic send a tech to my house for diagnosis. He determined that my house wiring was the culprit. I didn't agree w/ him because I had 2 lines going into the house(1 is 28ys old and 1 only 5yrs old). He said that they are bad but 2 lines going bad at same time didn't make sense to me. I order my own test kit from ebay and finally receive did my own troubleshooting this weekend. It turns out that the junction box is bad. I can't seem to find anyplace selling this. Anybody know where? I am using the line perfectly directly connected to ATT line but I don't want to use it this way w/o the grounding wire that was on the junction box. Good thing I didn't trust their tech, rewiring the house would have cost a bunch of money.
What you've got there is a decades old lightning arrester. There is a spark gap under each of the four bolts in the center of this thing and moisture and any number of other things can induce noise on your line, which is probably what's going on.
If that's what is on the side of your house, then call AT&T and have them install a modern Network Interface Device (NID) instead. They shouldn't charge you for it, since all service entrances these days are required to have a NID with a user friendly test jack inside. The Sonic tech should have recognized this and suggested the change.
If, on the other hand, this is just a junction point located beyond an existing NID, then simply remove it and tie the wires together, since the NID already has the lightning arresters inside.